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Sensitive determination of glycerol by derivatization using a HPLC-DAD method in biodiesel samples

Ahmed, Muhammad Arif, Khan, Ijaz, Hashim, Jamshed, Musharraf, Syed Ghulam
Analytical methods 2015 v.7 no.18 pp. 7805-7810
biodiesel, byproducts, catalysts, copper, derivatization, detection limit, diodes, esterification, glycerol, high performance liquid chromatography, organochlorine compounds, transesterification
Biodiesel is mainly produced through a transesterification reaction which yields biodiesel and glycerol, a by-product. This article describes the quantification of glycerol based on high performance liquid chromatography (HPLC) using a diode array detector (DAD) in various biodiesel samples through post-derivatization. Glycerol was converted into a UV active product i.e. glyceryl tribenzoate (GTB) through a simple and effective esterification reaction using benzoyl chloride and copper chloride as the catalyst under mild conditions. Optimized reaction conditions (affording a 90% yield) were obtained by using copper chloride (17 mol%), benzoyl chloride (12.0 equiv.) and triethyl amine (11.0 equiv.). The limit of detection and limit of quantification were found to be 0.23 μg mL⁻¹ and 0.76 μg mL⁻¹, respectively. The developed and validated HPLC-DAD method is sensitive, selective, reproducible and successfully applied for the quantification of glycerol in biodiesel from various sources.